A study of the colloidal stability of mixed abrasive slurries of silica and ceria nanoparticles for chemical mechanical polishing

• Author / Creator

  Lin, Fangjian

• Slurry stability is an important factor in Chemical Mechanical Polishing (CMP) efficiency. However, few studies have been done in this respect. In settling tests at pH 4, adding various amounts of ceria to colloidal silica slurries was shown to change the stability of the resulted mixed abrasive slurries (5 wt% of silica). Within a range of ceria-to-silica weight ratios, known as the transition range, the mixed abrasive slurries were observed to be unstable. A mathematical estimation based on zero net surface charge was proposed. The modification of particle surface charges through the attachment of positively charged ceria particles to negatively charged silica particles made the mixed slurries unstable. TEM images confirmed such attachments at pH 4. Compared to the slurries containing a single kind of particle, such mixed abrasive slurries were more effective in the CMP of PECVD oxide under the same conditions.

• Subjects / Keywords

  • Mixed abrasive slurries
  • Chemical mechanical polishing
  • Settling
  • Colloidal stability
  • Zeta potential

• Graduation date

  Fall 2011

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3967C

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.